American Chemical Society, Environmental Science and Technology, 3(50), p. 1118-1125, 2016
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Due to their static nature, physiologically-based in vitro methods often fail to provide sufficient sorption capacity for sparingly-soluble hydrophobic organic contaminants (HOCs), thereby underestimating their bioavailability in soils. The addition of a sorption sink to in vitro intestinal solutions can potentially mimic the dynamic intestinal uptake processes of HOCs, thereby increasing their desorption and bioaccessibility. However, the effectiveness of using sorption sinks to improve in vitro methods needs to be tested against in vivo data. In this study, Tenax was added as a sorption sink into the physiologically based extraction test (PBET), while DDT and its metabolites (DDTr) were investigated as typical HOCs. Tenax added at 0.010.2 g to PBET intestinal solution sorbed ~100% of DDTr in 6.3-19 min, indicating its ability to serve as an effective sorption sink. DDTr bioaccessibility in six contaminated soils, measured using the Tenax-improved PBET (TI-PBET; 2756%) was 3.4-22 fold greater than those obtained with the PBET (1.215%). In vivo DDTr relative bioavailability in contaminated soils was measured using a mouse model with values ranging from 17.9 to 65.4%. The feasibility of using the TI-PBET to predict DDTr relative bioavailability in contaminated soils was demonstrated by correlating in vivo and in vitro data. The correlation was improved from r2=0.36 (slope=2.1 for PBET) to r2=0.62 (slope=1.2 for TI-PBET), illustrating that the inclusion of Tenax as a sorption sink in the PBET intestinal phase was more effective at predicting DDTr relative bioavailability in contaminated soils.